The operation of small internal combustion engines which are used with a variety of tools and equipment, such as lawn and garden equipment, generators, out-board motors and the like require that the carburetor or fuel system be simple and capable of controlling operation in all possible positions of the engine. At the same time, the engine must be controlled so that it operates effectively and minimizes the exhaust of unburned fuel and oil to the atmosphere.
Present day small engines typically use conventional carburetors to control fuel delivery to the combustion chamber of the engine. Carburetors operate inefficiently in that unburned fuel is exhausted to the atmosphere resulting in pollution. Such systems, however, have been refined over many years and perform dependably and are of relatively low cost. The injection of fuel is more advantageous because it permits more accurate control of the amount and timing of the delivery of the fuel to the combustion chamber of the engine so that reduced emissions, fuel savings and increased power result. Typically, however, injection of fuel is controlled electronically. This is impractical for small engines because the control module alone could exceed the cost of the small engine.